(1. Northwest Institute of Eco-environment and Resources,State Key Laboratory of Frozen Soil Engineering,Chinese Academy of Sciences,Lanzhou,Gansu 730000,China;2. University of Chinese Academy of Sciences,Beijing 100049,China;3. College of Water Resources and Hydropower,Sichuan University,Chengdu,Sichuan 610065,China)
Abstract:In order to investigate the strengths and deformation properties of frozen sandy soils,a damage constitutive model under different confining pressures was established to describe the strain softening under lower confining pressures, the strain hardening under higher confining pressures,and the transition process from the internal micro-fissures to macro-shear bands. The strength criterion for the micro-element of frozen sandy soil is described by the modified Mohr-Coulomb yield criterion. Due to the discreteness and randomness of the internal micro-defects and micro-fissures,an assumption is made that the distribution of the micro-element strength for frozen sandy soil obeys Weibull function. Meanwhile,a stochastic damage constitutive model is established to reflect the whole breakage process under the ambient loads,based upon the theoretical knowledge of the statistical theory and the continuum damage mechanics(CDM). The parameters are determined from the cryogenic triaxial compression tests. The distribution parameters of n and F0,along with their variation with confining pressures,are discussed in detail. In addition,the cohesion c,the internal friction angle ? and the damage variable D are analyzed under the different confining pressures. Finally,comparisons between the predicted results and experimental data demonstrate that the modified model can simulate well the whole stress-strain curves,reflect the transition process from strain softening to strain hardening, predict reasonably the volumetric strain-axial strain curves,especially both the dilatant behaviors under relatively low confining pressures and the compressive characteristics under high confining pressures.
齐吉琳,马 巍. 冻土的力学性质及研究现状[J]. 岩土力学,2010,31(11):133-143.(QI Jilin,MA Wei. State-of-art of research on mechanical properties of frozen soils[J]. Rock and Soil Mechanics,2010,31(11):133-143.(in Chinese))
[3]
曹文贵,赵明华,刘成学. 岩石损伤统计强度理论研究[J]. 岩土工程学报,2004,26(6):820-823.(CAO Wengui,ZHAO Minghua,LIU Chengxue. A study on damage statistical strength theory for rock[J]. Chinese Journal of Geotechnical Engineering,2004,26(6):820-823.(in Chinese))
[4]
曹文贵,方祖烈,唐学军. 岩石损伤软化统计本构模型之研究[J]. 岩石力学与工程学报,1998,17(6):628-633.(CAO Wengui,FANG Zulie,TANG Xuejun. A study of statistical constitutive model for softening and damage rocks[J]. Chinese Journal of Rock Mechanics and Engineering,1998,17(6):628-633.(in Chinese))
[2]
徐卫亚,韦立德. 岩石损伤统计本构模型的研究[J]. 岩石力学与工程学报,2002,21(6):787-791.(XU Weiya,WEI Lide. Study on statistical damage constitutive model of rock[J]. Chinese Journal of Rock Mechanics and Engineering,2002,21(6):787-791.(in Chinese))
[5]
曹文贵,赵明华,唐学军. 岩石破裂过程的统计损伤模拟研究[J]. 岩土工程学报,2003,25(2):184-187.(CAO Wengui,ZHAO Minghua,TANG Xuejun. Study on simulation of statistical damage in the full process of rock failure[J]. Chinese Journal of Rock Mechanics and Engineering,2003,25(2):184-187.(in Chinese))
[7]
任建喜,葛修润. 单轴压缩岩石损伤演化细观机制及其本构模型研究[J]. 岩石力学与工程学报,2001,20(4):425-431.(REN Jianxi,GE Xiurun. Study of rock meso damage evolution law and its constitutive model under uniaxial compression loading[J]. Chinese Journal of Rock Mechanics and Engineering,2001,20(4):425-431. (in Chinese))
[9]
张淑娟,赖远明,苏新民,等. 风火山隧道冻融循环条件下岩石损伤扩展室内模拟研究[J]. 岩石力学与工程学报,2004,23(24): 4 105-4 111.(ZHANG Shujuan,LAI Yuanming,SU Xinmin,et al. A laboratory study on the damage propagation of rocks under freeze-thaw cycle condition[J]. Chinese Journal of Rock Mechanics and Engineering,2004,23(24):4 105-4 111.(in Chinese))
[11]
LAI Y M,LI J B,LI Q Z. Study on damage statistical constitutive model and stochastic simulation for warm ice-rich frozen silt[J]. Cold Regions Science and Technology,2012,71(2):102-110.
[12]
LAI Y M,LI S Y,QI J L. Strength distributions of warm frozen clay and its stochastic damage constitutive model[J]. Cold Regions Science and Technology,2008,53(2):200-215.
[15]
MA W,WU Z W,ZHANG L X. Analyses of process on the strength decrease in frozen soils under high confining pressures[J]. Cold Regions Science and Technology,1999,29(1):1-7.
[6]
曹文贵,赵明华,刘成学. 基于Weibull分布的岩石损伤软化模型及其修正方法研究[J]. 岩石力学与工程学报,2004,23(19):3 223- 3 231.(CAO Wengui,ZHAO Minghua,LIU Chengxue. Study on the model and its modifying method for rock softening and damage based on Weibull random distribution[J]. Chinese Journal of Rock Mechanics and Engineering,2004,23(19):3 223-3 231.(in Chinese))
[10]
任建喜. 冻结裂隙岩石加卸载破坏机制CT实时试验[J]. 岩土工程学报,2004,26(5):641-644.(REN Jianxi. Real-time CT test of damage failure mechanism of frozen cracked rock in loading and unloading condition[J]. Chinese Journal of Geotechnical Engineering,2004,26(5):641-644.(in Chinese))
[20]
LIAO M K,LAI Y M,YANG J J. Experimental study and statistical theory of creep behavior of warm frozen silt[J]. KSCE Journal of Civil Engineering,2016,20(6):2 333-2 344.
[8]
张继周,缪林昌,杨振峰. 冻融条件下岩石损伤劣化机制和力学特性研究[J]. 岩石力学与工程学报,2008,27(8):1 688-1 694. (ZHANG Jizhou,MIAO Linchang,YANG Zhenfeng. Research on rock degradation and deterioration mechanisms and mechanical characteristics under cyclic freezing-thawing[J]. Chinese Journal of Rock Mechanics and Engineering,2008,27(8):1 688-1 694.(in Chinese))
[18]
刘恩龙,罗开泰,张树祎. 初始应力各向异性结构性土的二元介质模型[J]. 岩土力学,2013,34(11):3 103-3 109.(LIU Enlong,LUO Kaitai,ZHANG Shuyi,Binary medium model for structured soils with initial stress-induced anisotropy[J]. Rock and Soil Mechanics,2013,34(11):3 103-3 109.(in Chinese))
[13]
LI S Y,LAI Y M,ZHANG S J. An improved statistical damage constitutive model for warm frozen clay based on Mohr-Coulomb criterion[J]. Cold Regions Science and Technology,2009,57(2):154-159.
[14]
LAI Y M,YANG Y G,CHANG X X,et al. Strength criterion and elastoplastic constitutive model of frozen silt in generalized plastic- mechanics[J]. International Journal of Plasticity,2010,26(10):1 461-1 484.
[16]
QI J L,MA W. A new criterion for strength of frozen sand under quick triaxial compression considering effect of confining pressure[J]. Acta Geote-chnica,2007,(2):221-226.
[17]
LAI Y M,LIAO M K,HU K. A constitutive model of frozen saline sandy soil based on energy dissipation theory[J]. International Journal of Plasticity,2016,78:84-113.
[19]
LIU E L,YU H S,ZHOU C,et al. A binary-medium constitutive model for artificially structured soils based on the disturbed state concept and homogenization theory[J]. International Journal of Geomechanics,2016,17(7):1-15.